Columns

Menopause: we know it as a thing to be dreaded — a word to be uttered, not spoken. It brings our mothers’ and grandmothers’ hot flushes and mood swings, and is probably the reason your mum gave you a little too much grief about breaking curfew or having a messy room. Women don’t typically look forward to it, but menopause is actually a rare phenomenon, and could provide a great deal of value in post-reproductive life.

Humans are one of only three species to experience menopause; the two others are short-finned pilot whales and killer whales. All other species, from ants to elephants, are able to give birth until they die. Both humans and these two types of whales spend a considerable amount of time in post-reproductive life — humans live, on average, up to 30 years after menopause, and female killer whales have a hefty 50 years of post-reproductive life.

Evolutionary scientists have found this concept a bit puzzling. Why do our bodies retire the ability to have children? Shouldn’t the nature of our biology have us breeding steadily, so as to further our species? One popular notion is the “grandmother hypothesis”, which states that children become more successful adults with the care of both their mother and grandmother; therefore, a woman’s later years are most effectively spent raising grandchildren.

To help solve the mysteries of the post-reproductive female, Lauren Brent and her team from the Centre for Research in Animal Behaviour at the University of Exeter in the UK have been observing patterns of elderly killer whales off the western coast of the United States. Their findings show that post-reproductive females (the oldest of whom is 103 years old; males only live to be about 50) have a wealth of ecological knowledge, accumulated with age, which they pass down to the kin of the pod.

Brent and her team observed that menopausal female whales led the pod to locate and hunt salmon more often than males. Salmon make up 97% of a killer whale’s diet. They are unpredictable, with migration patterns that depend on the seasons, the year and the tides. An orca which has lived long enough to watch the patterns for almost a century is more helpful in locating dinner than any other member of the pod.

The purpose of post-reproductive female orcas stretches beyond raising kin; it improves the survival rate of the entire pod. Female orcas are valued for their ecological knowledge and leadership. They are trusted and valued by other members of the pod. Brent’s research suggests that the idea of a post-reproductive woman “losing” the ability to have a child might not actually be a loss — it might, in fact, be the time when her life is most valuable.